In work places of machining processing, for the purpose of making parts from raw materials, machine tools are necessary. Even up to now, most of the machine tools have been mainly operated and monitored on-line by operators. Thus, the safety measures are crucially important in the work places. As the operators turn on the machine tools, but are reckless enough not to remove non-operational subjects, for example T-shaped chuck wrench used for work loading, this results in operator's serious accidental injury. Therefore, enhancing the protective measures is a vital issue of safety improvement necessary in the work places where the machine tools exist. Moreover, this safety issue is more critical in the places where students take practical training.
Most of the means for enhancing the safety measures of machine tools is to install transparent safety masks or sensors around the machine tools. There is no otherwise positive protective measure. On the other hand, the protection received from transparent masks is limited. For one thing, the transparent masks build up a safety zone only in a specific area and provide partial protection; for the other, the protection from the safety mask is extremely weak. According to the experiences in the work places, the ejective angle and destructive power of a non-operational piece, for example a T-shaped chuck wrench, caused through operator's negligence, are far beyond what the transparent mask can control. It is obvious that a simple transparent mask cannot provide sufficient protection.
In other instances, to enhance the safety concerns of machine tools, some safety sensing device is adopted on the work bench of the machine tool. Somehow its sensing scope is constrained. For one thing, there are many dead zones for the safety sensor. Furthermore, the safety sensor cannot judge whether a non-operational subject, for example a T-shaped chuck wrench, has been removed to a relatively safe place. Especially for randomly placed work-loading device, for example a T-shaped chuck wrench, the safety sensor cannot identify its location in relation to operator's position. No base can then be established to judge whether a safety concern is to be raised. Hence, the abovementioned methods fail to provide an effective and positive protection for the operators in manipulating machine tools.
It is found that human factor dominates the occurrences of occupational injury. Thus, apart from giving an ideal pre-occupational safety training, the design of an effective and positive safety apparatus is a priority for the working environments where students are receiving practical training, which at the same time helps reduce the occupational injury to a minimal extent.